// Watcher watches a set of files, delivering events to a channel.
type Watcher struct {
- Events chan Event
- Errors chan error
- mu sync.Mutex // Map access
- fd int
- poller *fdPoller
- watches map[string]*watch // Map of inotify watches (key: path)
- paths map[int]string // Map of watched paths (key: watch descriptor)
- done chan struct{} // Channel for sending a "quit message" to the reader goroutine
- doneResp chan struct{} // Channel to respond to Close
+ fd int // https://github.com/golang/go/issues/26439 can't call .Fd() on os.FIle or Read will no longer return on Close()
+ Events chan Event
+ Errors chan error
+ mu sync.Mutex // Map access
+ inotifyFile *os.File
+ watches map[string]*watch // Map of inotify watches (key: path)
+ paths map[int]string // Map of watched paths (key: watch descriptor)
+ done chan struct{} // Channel for sending a "quit message" to the reader goroutine
+ doneResp chan struct{} // Channel to respond to Close
}
// NewWatcher establishes a new watcher with the underlying OS and begins waiting for events.
func NewWatcher() (*Watcher, error) {
// Create inotify fd
- fd, errno := unix.InotifyInit1(unix.IN_CLOEXEC)
+ // Need to set the FD to nonblocking mode in order for SetDeadline methods to work
+ // Otherwise, blocking i/o operations won't terminate on close
+ fd, errno := unix.InotifyInit1(unix.IN_CLOEXEC | unix.IN_NONBLOCK)
if fd == -1 {
return nil, errno
}
- // Create epoll
- poller, err := newFdPoller(fd)
- if err != nil {
- unix.Close(fd)
- return nil, err
- }
+
w := &Watcher{
- fd: fd,
- poller: poller,
- watches: make(map[string]*watch),
- paths: make(map[int]string),
- Events: make(chan Event),
- Errors: make(chan error),
- done: make(chan struct{}),
- doneResp: make(chan struct{}),
+ fd: fd,
+ inotifyFile: os.NewFile(uintptr(fd), ""),
+ watches: make(map[string]*watch),
+ paths: make(map[int]string),
+ Events: make(chan Event),
+ Errors: make(chan error),
+ done: make(chan struct{}),
+ doneResp: make(chan struct{}),
}
go w.readEvents()
close(w.done)
w.mu.Unlock()
- // Wake up goroutine
- w.poller.wake()
+ // Causes any blocking reads to return with an error, provided the file still supports deadline operations
+ err := w.inotifyFile.Close()
+ if err != nil {
+ return err
+ }
// Wait for goroutine to close
<-w.doneResp
func (w *Watcher) readEvents() {
var (
buf [unix.SizeofInotifyEvent * 4096]byte // Buffer for a maximum of 4096 raw events
- n int // Number of bytes read with read()
errno error // Syscall errno
- ok bool // For poller.wait
)
defer close(w.doneResp)
defer close(w.Errors)
defer close(w.Events)
- defer unix.Close(w.fd)
- defer w.poller.close()
for {
// See if we have been closed.
return
}
- ok, errno = w.poller.wait()
- if errno != nil {
+ n, err := w.inotifyFile.Read(buf[:])
+ switch {
+ case errors.Unwrap(err) == os.ErrClosed:
+ return
+ case err != nil:
select {
- case w.Errors <- errno:
+ case w.Errors <- err:
case <-w.done:
return
}
continue
}
- if !ok {
- continue
- }
-
- n, errno = unix.Read(w.fd, buf[:])
- // If a signal interrupted execution, see if we've been asked to close, and try again.
- // http://man7.org/linux/man-pages/man7/signal.7.html :
- // "Before Linux 3.8, reads from an inotify(7) file descriptor were not restartable"
- if errno == unix.EINTR {
- continue
- }
-
- // unix.Read might have been woken up by Close. If so, we're done.
- if w.isClosed() {
- return
- }
-
if n < unix.SizeofInotifyEvent {
var err error
if n == 0 {
+++ /dev/null
-// Copyright 2015 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build linux
-// +build linux
-
-package fsnotify
-
-import (
- "errors"
-
- "golang.org/x/sys/unix"
-)
-
-type fdPoller struct {
- fd int // File descriptor (as returned by the inotify_init() syscall)
- epfd int // Epoll file descriptor
- pipe [2]int // Pipe for waking up
-}
-
-func emptyPoller(fd int) *fdPoller {
- poller := new(fdPoller)
- poller.fd = fd
- poller.epfd = -1
- poller.pipe[0] = -1
- poller.pipe[1] = -1
- return poller
-}
-
-// Create a new inotify poller.
-// This creates an inotify handler, and an epoll handler.
-func newFdPoller(fd int) (*fdPoller, error) {
- var errno error
- poller := emptyPoller(fd)
- defer func() {
- if errno != nil {
- poller.close()
- }
- }()
-
- // Create epoll fd
- poller.epfd, errno = unix.EpollCreate1(unix.EPOLL_CLOEXEC)
- if poller.epfd == -1 {
- return nil, errno
- }
- // Create pipe; pipe[0] is the read end, pipe[1] the write end.
- errno = unix.Pipe2(poller.pipe[:], unix.O_NONBLOCK|unix.O_CLOEXEC)
- if errno != nil {
- return nil, errno
- }
-
- // Register inotify fd with epoll
- event := unix.EpollEvent{
- Fd: int32(poller.fd),
- Events: unix.EPOLLIN,
- }
- errno = unix.EpollCtl(poller.epfd, unix.EPOLL_CTL_ADD, poller.fd, &event)
- if errno != nil {
- return nil, errno
- }
-
- // Register pipe fd with epoll
- event = unix.EpollEvent{
- Fd: int32(poller.pipe[0]),
- Events: unix.EPOLLIN,
- }
- errno = unix.EpollCtl(poller.epfd, unix.EPOLL_CTL_ADD, poller.pipe[0], &event)
- if errno != nil {
- return nil, errno
- }
-
- return poller, nil
-}
-
-// Wait using epoll.
-// Returns true if something is ready to be read,
-// false if there is not.
-func (poller *fdPoller) wait() (bool, error) {
- // 3 possible events per fd, and 2 fds, makes a maximum of 6 events.
- // I don't know whether epoll_wait returns the number of events returned,
- // or the total number of events ready.
- // I decided to catch both by making the buffer one larger than the maximum.
- events := make([]unix.EpollEvent, 7)
- for {
- n, errno := unix.EpollWait(poller.epfd, events, -1)
- if n == -1 {
- if errno == unix.EINTR {
- continue
- }
- return false, errno
- }
- if n == 0 {
- // If there are no events, try again.
- continue
- }
- if n > 6 {
- // This should never happen. More events were returned than should be possible.
- return false, errors.New("epoll_wait returned more events than I know what to do with")
- }
- ready := events[:n]
- epollhup := false
- epollerr := false
- epollin := false
- for _, event := range ready {
- if event.Fd == int32(poller.fd) {
- if event.Events&unix.EPOLLHUP != 0 {
- // This should not happen, but if it does, treat it as a wakeup.
- epollhup = true
- }
- if event.Events&unix.EPOLLERR != 0 {
- // If an error is waiting on the file descriptor, we should pretend
- // something is ready to read, and let unix.Read pick up the error.
- epollerr = true
- }
- if event.Events&unix.EPOLLIN != 0 {
- // There is data to read.
- epollin = true
- }
- }
- if event.Fd == int32(poller.pipe[0]) {
- if event.Events&unix.EPOLLHUP != 0 {
- // Write pipe descriptor was closed, by us. This means we're closing down the
- // watcher, and we should wake up.
- }
- if event.Events&unix.EPOLLERR != 0 {
- // If an error is waiting on the pipe file descriptor.
- // This is an absolute mystery, and should never ever happen.
- return false, errors.New("Error on the pipe descriptor.")
- }
- if event.Events&unix.EPOLLIN != 0 {
- // This is a regular wakeup, so we have to clear the buffer.
- err := poller.clearWake()
- if err != nil {
- return false, err
- }
- }
- }
- }
-
- if epollhup || epollerr || epollin {
- return true, nil
- }
- return false, nil
- }
-}
-
-// Close the write end of the poller.
-func (poller *fdPoller) wake() error {
- buf := make([]byte, 1)
- n, errno := unix.Write(poller.pipe[1], buf)
- if n == -1 {
- if errno == unix.EAGAIN {
- // Buffer is full, poller will wake.
- return nil
- }
- return errno
- }
- return nil
-}
-
-func (poller *fdPoller) clearWake() error {
- // You have to be woken up a LOT in order to get to 100!
- buf := make([]byte, 100)
- n, errno := unix.Read(poller.pipe[0], buf)
- if n == -1 {
- if errno == unix.EAGAIN {
- // Buffer is empty, someone else cleared our wake.
- return nil
- }
- return errno
- }
- return nil
-}
-
-// Close all poller file descriptors, but not the one passed to it.
-func (poller *fdPoller) close() {
- if poller.pipe[1] != -1 {
- unix.Close(poller.pipe[1])
- }
- if poller.pipe[0] != -1 {
- unix.Close(poller.pipe[0])
- }
- if poller.epfd != -1 {
- unix.Close(poller.epfd)
- }
-}
+++ /dev/null
-// Copyright 2015 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build linux
-// +build linux
-
-package fsnotify
-
-import (
- "testing"
- "time"
-
- "golang.org/x/sys/unix"
-)
-
-type testFd [2]int
-
-func makeTestFd(t *testing.T) testFd {
- var tfd testFd
- errno := unix.Pipe(tfd[:])
- if errno != nil {
- t.Fatalf("Failed to create pipe: %v", errno)
- }
- return tfd
-}
-
-func (tfd testFd) fd() int {
- return tfd[0]
-}
-
-func (tfd testFd) closeWrite(t *testing.T) {
- errno := unix.Close(tfd[1])
- if errno != nil {
- t.Fatalf("Failed to close write end of pipe: %v", errno)
- }
-}
-
-func (tfd testFd) put(t *testing.T) {
- buf := make([]byte, 10)
- _, errno := unix.Write(tfd[1], buf)
- if errno != nil {
- t.Fatalf("Failed to write to pipe: %v", errno)
- }
-}
-
-func (tfd testFd) get(t *testing.T) {
- buf := make([]byte, 10)
- _, errno := unix.Read(tfd[0], buf)
- if errno != nil {
- t.Fatalf("Failed to read from pipe: %v", errno)
- }
-}
-
-func (tfd testFd) close() {
- unix.Close(tfd[1])
- unix.Close(tfd[0])
-}
-
-func makePoller(t *testing.T) (testFd, *fdPoller) {
- tfd := makeTestFd(t)
- poller, err := newFdPoller(tfd.fd())
- if err != nil {
- t.Fatalf("Failed to create poller: %v", err)
- }
- return tfd, poller
-}
-
-func TestPollerWithBadFd(t *testing.T) {
- _, err := newFdPoller(-1)
- if err != unix.EBADF {
- t.Fatalf("Expected EBADF, got: %v", err)
- }
-}
-
-func TestPollerWithData(t *testing.T) {
- tfd, poller := makePoller(t)
- defer tfd.close()
- defer poller.close()
-
- tfd.put(t)
- ok, err := poller.wait()
- if err != nil {
- t.Fatalf("poller failed: %v", err)
- }
- if !ok {
- t.Fatalf("expected poller to return true")
- }
- tfd.get(t)
-}
-
-func TestPollerWithWakeup(t *testing.T) {
- tfd, poller := makePoller(t)
- defer tfd.close()
- defer poller.close()
-
- err := poller.wake()
- if err != nil {
- t.Fatalf("wake failed: %v", err)
- }
- ok, err := poller.wait()
- if err != nil {
- t.Fatalf("poller failed: %v", err)
- }
- if ok {
- t.Fatalf("expected poller to return false")
- }
-}
-
-func TestPollerWithClose(t *testing.T) {
- tfd, poller := makePoller(t)
- defer tfd.close()
- defer poller.close()
-
- tfd.closeWrite(t)
- ok, err := poller.wait()
- if err != nil {
- t.Fatalf("poller failed: %v", err)
- }
- if !ok {
- t.Fatalf("expected poller to return true")
- }
-}
-
-func TestPollerWithWakeupAndData(t *testing.T) {
- tfd, poller := makePoller(t)
- defer tfd.close()
- defer poller.close()
-
- tfd.put(t)
- err := poller.wake()
- if err != nil {
- t.Fatalf("wake failed: %v", err)
- }
-
- // both data and wakeup
- ok, err := poller.wait()
- if err != nil {
- t.Fatalf("poller failed: %v", err)
- }
- if !ok {
- t.Fatalf("expected poller to return true")
- }
-
- // data is still in the buffer, wakeup is cleared
- ok, err = poller.wait()
- if err != nil {
- t.Fatalf("poller failed: %v", err)
- }
- if !ok {
- t.Fatalf("expected poller to return true")
- }
-
- tfd.get(t)
- // data is gone, only wakeup now
- err = poller.wake()
- if err != nil {
- t.Fatalf("wake failed: %v", err)
- }
- ok, err = poller.wait()
- if err != nil {
- t.Fatalf("poller failed: %v", err)
- }
- if ok {
- t.Fatalf("expected poller to return false")
- }
-}
-
-func TestPollerConcurrent(t *testing.T) {
- tfd, poller := makePoller(t)
- defer tfd.close()
- defer poller.close()
-
- oks := make(chan bool)
- live := make(chan bool)
- defer close(live)
- go func() {
- defer close(oks)
- for {
- ok, err := poller.wait()
- if err != nil {
- t.Errorf("poller failed: %v", err)
- }
- oks <- ok
- if !<-live {
- return
- }
- }
- }()
-
- // Try a write
- select {
- case <-time.After(50 * time.Millisecond):
- case <-oks:
- t.Fatalf("poller did not wait")
- }
- tfd.put(t)
- if !<-oks {
- t.Fatalf("expected true")
- }
- tfd.get(t)
- live <- true
-
- // Try a wakeup
- select {
- case <-time.After(50 * time.Millisecond):
- case <-oks:
- t.Fatalf("poller did not wait")
- }
- err := poller.wake()
- if err != nil {
- t.Fatalf("wake failed: %v", err)
- }
- if <-oks {
- t.Fatalf("expected false")
- }
- live <- true
-
- // Try a close
- select {
- case <-time.After(50 * time.Millisecond):
- case <-oks:
- t.Fatalf("poller did not wait")
- }
- tfd.closeWrite(t)
- if !<-oks {
- t.Fatalf("expected true")
- }
- tfd.get(t)
-
- // wait for all goroutines for finish.
- live <- false
- <-oks
-}
fd.Close()
checkEvent(Remove)
}
+
+func TestINotifyNoBlockingSyscalls(t *testing.T) {
+ getThreads := func() int {
+ d := fmt.Sprintf("/proc/%d/task", os.Getpid())
+ ls, err := os.ReadDir(d)
+ if err != nil {
+ t.Fatalf("reading %q: %s", d, err)
+ }
+ return len(ls)
+ }
+
+ w, err := NewWatcher()
+ if err != nil {
+ t.Fatalf("Failed to create watcher: %v", err)
+ }
+
+ startingThreads := getThreads()
+ // Call readEvents a bunch of times; if this function has a blocking raw syscall, it'll create many new kthreads
+ for i := 0; i <= 60; i++ {
+ go w.readEvents()
+ }
+
+ // Bad synchronization mechanism
+ time.Sleep(time.Second * 2)
+
+ endingThreads := getThreads()
+
+ // Did we spawn any new threads?
+ if diff := endingThreads - startingThreads; diff > 0 {
+ t.Fatalf("Got a nonzero diff %v. starting: %v. ending: %v", diff, startingThreads, endingThreads)
+ }
+}
projects / fsnotify.git / commitdiff